1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device and a method of manufacturing a bonding sheet. In particular, the present invention relates to a method of affixing a bonding sheet to a semiconductor wafer and a method of manufacturing a bonding sheet in connection with such affixing method. Moreover, the present invention relates to a semiconductor device having such bonding sheet.
2. Background Information
A method of cutting a semiconductor wafer into semiconductor device chips while the semiconductor wafer has a bonding sheet affixed thereto is known in the prior art (e.g. Japanese Laid-Open Patent Application No. 2000-340526 (hereinafter to be referred to as Patent Reference 1)). FIG. 1A and FIG. 1B are diagrams showing a conventional method of affixing a bonding sheet to a semiconductor wafer.
As shown in FIG. 1A, in this conventional example, a bonding sheet 911 rolled up in a sheet supply spool 910 is used. First, a semiconductor wafer 940 having its back surface facing upward (i.e., the side opposite to the surface where circuit elements are formed) is placed on a wafer vacuum contact table 930 having a heater 931 built therein. Then, the bonding sheet 911 drawn out from the sheet supply spool 910 is pressed into the back surface of the semiconductor wafer 940 by a sheet affixing roller 950. Here, the bonding sheet 911 should produce viscosity when heated. Therefore, in pressing the drawn out bonding sheet 911 onto the back surface of the semiconductor wafer 940, the semiconductor wafer 940 is heated by the heater 931 in order to have the bonding sheet 911 affixed on the back surface of the semiconductor wafer 940. An excess portion (hereinafter to be referred to as an excess sheet) of the bonding sheet 911 drawn out from the sheet supply spool 910 is taken up by a collecting spool 920 (hereinafter to be referred to as an excess sheet collecting spool).
The semiconductor wafer 940 having the bonding sheet 911 affixed thereto in the above described manner (q.v. FIG. 1B) is cut into chips of individual semiconductor devices using a dicing blade, for instance. After that, each chip of the semiconductor device is attached to a lead frame etc. using the bonding sheet 911 on the back surface thereof.
However, the conventional method as described above requires a number of expensive devices such as the sheet supply spool 910, the excess sheet connection spool 920, the wafer vacuum contact table 930 with the built-in heater 931 etc. Accordingly, equipment investment becomes costly, which makes it difficult to manufacture a semiconductor device at low cost.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved method of manufacturing a semiconductor device, an improved bonding sheet for use in a semiconductor device and an improved method of manufacturing a bonding sheet. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.